From d8e0420603cf1ce9cb459c00ea0b7337de41b968 Mon Sep 17 00:00:00 2001 From: Jeremy Fitzhardinge Date: Mon, 9 Feb 2009 12:05:46 -0800 Subject: xen: define BIOVEC_PHYS_MERGEABLE() Impact: allow Xen control of bio merging When running in Xen domain with device access, we need to make sure the block subsystem doesn't merge requests across pages which aren't machine physically contiguous. To do this, we define our own BIOVEC_PHYS_MERGEABLE. When CONFIG_XEN isn't enabled, or we're not running in a Xen domain, this has identical behaviour to the normal implementation. When running under Xen, we also make sure the underlying machine pages are the same or adjacent. Signed-off-by: Jeremy Fitzhardinge Signed-off-by: Konrad Rzeszutek Wilk --- drivers/xen/Makefile | 2 +- drivers/xen/biomerge.c | 13 +++++++++++++ 2 files changed, 14 insertions(+), 1 deletion(-) create mode 100644 drivers/xen/biomerge.c (limited to 'drivers/xen') diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile index fcaf838f54be..b47f5da674d3 100644 --- a/drivers/xen/Makefile +++ b/drivers/xen/Makefile @@ -1,4 +1,4 @@ -obj-y += grant-table.o features.o events.o manage.o +obj-y += grant-table.o features.o events.o manage.o biomerge.o obj-y += xenbus/ nostackp := $(call cc-option, -fno-stack-protector) diff --git a/drivers/xen/biomerge.c b/drivers/xen/biomerge.c new file mode 100644 index 000000000000..ba6eda4b5143 --- /dev/null +++ b/drivers/xen/biomerge.c @@ -0,0 +1,13 @@ +#include +#include +#include + +bool xen_biovec_phys_mergeable(const struct bio_vec *vec1, + const struct bio_vec *vec2) +{ + unsigned long mfn1 = pfn_to_mfn(page_to_pfn(vec1->bv_page)); + unsigned long mfn2 = pfn_to_mfn(page_to_pfn(vec2->bv_page)); + + return __BIOVEC_PHYS_MERGEABLE(vec1, vec2) && + ((mfn1 == mfn2) || ((mfn1+1) == mfn2)); +} -- cgit v1.2.2